menstrual cycle

• stages:

  1. menstruation starts - uterus lining breaks down for four days
  2. uterus lining builds up again from day 4 to 14, into layer of blood to recieve fertilised egg
  3. egg develops and released from ovary at day 14 - ovulation
  4. wall maintained until day 28 - if there is no fertilised egg, lining of uterus breaks down
• the menstrual cycle is controlled by:

  • FSH
  • oestrogen
  • LH
  • progesterone
• FSH:

  • follicle stimulating hormone
  • produced by pituitary gland
  • causes egg to mature in ovary, into follicle
  • stimulates ovaries to produce oestrogen
• oestrogen:

  • produced in ovaries
  • causes lining of uterus to grow
  • stimulates release of LH
  • inhibits release of FSH
• LH:

  • luteinising hormone
  • produced by pituitary gland
  • stimulates release of egg at day 14
• progestrone:

  • produced in ovaries by remians of follicle after ovulation
  • maintains lining of uterus
  • inhibits release of LH and FSH